1. Field of the Invention
The present invention relates to a light source unit and a projector which includes this light source unit.
2. Description of the Related Art
In these days, data projectors are used on many occasions as image projection apparatuses which project images including images of screens and video images of personal computers, as well as images based on image data which is stored in memory cards on to a screen.
In projectors of the type described above, conventionally, projectors using a high-intensity discharge lamp as a light source have been the mainstream of projectors. However, in recent years, there have been made many developments and proposals on projectors which use, as a light emitting element of a light source, a light emitting diode (LED), a laser beam emitter, a device utilizing organic EL technology or luminescent materials.
For example, Japanese Unexamined Patent Publication No. 2004-341105 (JP-A-2004-341105) proposes a light source unit in which a red luminescent material layer, a green luminescent material layer and a blue luminescent material layer are provided circumferentially in an end-to-end fashion on a front surface of a luminescent wheel made up of a disc having light transmission characteristics and a dichroic filter which transmits ultraviolet light and reflects visible light is disposed on a rear surface of the luminescent wheel, so that light source light of red, green and blue wavelength bands is generated by shining ultraviolet light on to the luminescent material layers from the rear surface of the luminescent wheel.
In addition, the applicant of this patent application also proposed in the previous patent application a light source unit which includes a laser beam emitter as an excitation light source and a luminescent wheel on which a luminescent layer is formed on a reflecting surface.
In this proposal, a laser beam is shone on to the luminescent material layer from the laser beam emitter and luminescent luminous light which is emitted from a luminescent material in the luminescent material layer is made use of as light source light by being extracted from a surface on the same side as the surface on to which the laser beam is shone.